Attopascal is 1e-18 pascal units.
Attopascals to Pascals Converter — aPa to Pa
Convert Attopascal (aPa) to Pascal (Pa) using the exact conversion factor (1 attopascal = 1e-18 pascal). See the formula, worked examples, conversion table, history, and common uses.
Attopascals to Pascals converter
Converter
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mercury columns, water columns, and engineering pressure units.
Context values
Some unit families need one extra value for a physically accurate result.
The pascal is one newton per square meter.
Result = input x 1e-18 / 1.
Pressure uses the pascal as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Attopascals to Pascals
Attopascal and Pascal both show up on pressure gauges — psi is standard on US tire and tool specifications, while bar is the everyday pressure unit across most of the rest of the world. Specifically: Attopascal is 1e-18 pascal units, and the pascal is one newton per square meter.
Formula
pascals = attopascals × 1e-18
This factor comes from each unit's defined relationship to the category's base unit: 1 attopascal equals 1e-18 base units, and 1 pascal equals 1 base unit, so dividing one by the other gives the direct attopascal-to-pascal factor of 1e-18.
Simple example
1 aPa × 1e-18 = 1e-18 Pa
1 attopascal = 1e-18 pascals.
Real-world example
35 aPa × 1e-18 = 3.5e-17 Pa
35 attopascals = 3.5e-17 pascals.
Conversion table
| Attopascal (aPa) | Pascal (Pa) |
|---|---|
| 1 aPa | 1e-18 Pa |
| 5 aPa | 5e-18 Pa |
| 10 aPa | 1e-17 Pa |
| 25 aPa | 2.5e-17 Pa |
| 50 aPa | 5e-17 Pa |
| 100 aPa | 1e-16 Pa |
Reverse conversion: Pascal to Attopascal
1e-18 Pa × 1e+18 = 1 aPa
1e-18 pascals = 1 attopascal.
attopascals = pascals × 1e+18
For a page dedicated to this direction, see Pascal to Attopascal.
Understanding the Attopascal (aPa)
Attopascal is 1e-18 pascal units.
Understanding the Pascal
Pascal (Pa) measures pressure. The pascal is the SI derived unit of pressure: one newton of force per square meter. It is classified as a SI derived unit.
Where it's used: Standard scientific pressure unit worldwide
Uses of the Pascal today
- Scientific and engineering pressure measurement worldwide
- Meteorology (often as hectopascals, equivalent to millibars)
- Material science (stress and strength, typically in megapascals)
History of the Pascal
The pascal is named after Blaise Pascal, whose 17th-century experiments clarified the physics of fluid pressure and vacuum. It was adopted as the SI derived unit of pressure in 1971, replacing the older, non-coherent CGS pressure units used in much scientific work up to that point.
Historical origin. Pascal was not the invention of a single named person; it developed through the process described above.
Pascal — sources
- BIPM SI Brochure — Coherent derived units — Defines the pascal as the SI unit of pressure.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many pascals are in 1 attopascal?
1 attopascal equals 1e-18 pascals, using the exact defined conversion factor rather than an estimate.
How do I convert attopascal to pascal?
Multiply the attopascal value by 1e-18. The converter above does this instantly to whatever precision you set.
How do I convert pascal back to attopascal?
Use the reverse factor: 1 pascal equals 1e+18 attopascals. You can also use the swap control in the converter above to flip the direction instantly.
What is a attopascal?
Attopascal (aPa) is a unit of pressure.
What is a pascal?
Pascal (Pa) measures pressure. The pascal is the SI derived unit of pressure: one newton of force per square meter. It is classified as a SI derived unit.
Is the attopascal to pascal conversion exact?
Yes. Both attopascal and pascal are defined by fixed standards rather than physical artifacts, so the factor of 1e-18 used above is exact to as many digits as you choose to display.